These days I've kept on working on WriteArea and today I've uploaded the fifth alpha version. This version is quite better with regards to the detection of other Rich Editors and finally removes a little code that I added for their detection but I knew that shouldn't be included in a final version.
Most important: this version includes an option in the preferences to open the editor in a bottom pane of the page. I've borrowed the close button from the AdBlock Plus skin and I will try to confirm that this is OK before releasing the final version.
There's a little problem with this bottom pane: it isn't aware of tabs, so when you switch tabs it remains there and it's a little annoying, because if you close the pane you might lose all the content. I'll try to find a solution to this problem, although I'm getting already a little tired of so much work in this extension for the last few days.